e-PLASCOM - Plàstics i Compòsits Ecològicshttp://hdl.handle.net/2117/1152752024-03-28T21:34:58Z2024-03-28T21:34:58ZIce-template crosslinked PVA aerogels modified with tannic acid and sodium alginateCruz Jesús, Lucía Guadalupe de laAbt, Tobias MartinLeón Albiter, NoelWang, LiangSánchez Soto, Miguelhttp://hdl.handle.net/2117/3751592022-10-30T19:04:41Z2022-10-27T12:50:41ZIce-template crosslinked PVA aerogels modified with tannic acid and sodium alginate
Cruz Jesús, Lucía Guadalupe de la; Abt, Tobias Martin; León Albiter, Noel; Wang, Liang; Sánchez Soto, Miguel
With the commitment to reducing environmental impact, bio-based and biodegradable aerogels may be one approach when looking for greener solutions with similar attributes to current foam-like materials. This study aimed to enhance the mechanical, thermal, and flame-retardant behavior of poly(vinyl alcohol) (PVA) aerogels by adding sodium alginate (SA) and tannic acid (TA). Aerogels were obtained by freeze-drying and post-ion crosslinking through calcium chloride (CaCl2) and boric acid (H3BO3) solutions. The incorporation of TA and SA enhanced the PVA aerogel’s mechanical properties, as shown by their high compressive specific moduli, reaching up to a six-fold increase after crosslinking and drying. The PVA/TA/SA aerogels presented a thermal conductivity of 0.043 to 0.046 W/m·K, while crosslinked ones showed higher values (0.049 to 0.060 W/m·K). Under TGA pyrolytic conditions, char layer formation reduced the thermal degradation rate of samples. After crosslinking, a seven-fold decrease in the thermal degradation rate was observed, confirming the high thermal stability of the formed foams. Regarding flammability, aerogels were tested through cone calorimetry. PVA/TA/SA aerogels showed a significant drop in the main parameters, such as the heat release rate (HRR) and the fire growth (FIGRA). The ion crosslinking resulted in a further reduction, confirming the improvement in the fire resistance of the modified compositions
2022-10-27T12:50:41ZCruz Jesús, Lucía Guadalupe de laAbt, Tobias MartinLeón Albiter, NoelWang, LiangSánchez Soto, MiguelWith the commitment to reducing environmental impact, bio-based and biodegradable aerogels may be one approach when looking for greener solutions with similar attributes to current foam-like materials. This study aimed to enhance the mechanical, thermal, and flame-retardant behavior of poly(vinyl alcohol) (PVA) aerogels by adding sodium alginate (SA) and tannic acid (TA). Aerogels were obtained by freeze-drying and post-ion crosslinking through calcium chloride (CaCl2) and boric acid (H3BO3) solutions. The incorporation of TA and SA enhanced the PVA aerogel’s mechanical properties, as shown by their high compressive specific moduli, reaching up to a six-fold increase after crosslinking and drying. The PVA/TA/SA aerogels presented a thermal conductivity of 0.043 to 0.046 W/m·K, while crosslinked ones showed higher values (0.049 to 0.060 W/m·K). Under TGA pyrolytic conditions, char layer formation reduced the thermal degradation rate of samples. After crosslinking, a seven-fold decrease in the thermal degradation rate was observed, confirming the high thermal stability of the formed foams. Regarding flammability, aerogels were tested through cone calorimetry. PVA/TA/SA aerogels showed a significant drop in the main parameters, such as the heat release rate (HRR) and the fire growth (FIGRA). The ion crosslinking resulted in a further reduction, confirming the improvement in the fire resistance of the modified compositionsCharacteristic time of strain induced crystallization of crosslinked natural rubberCandau, NicolasChazeau, LaurentChenal, Jean MarcGauthier, CatherineFerreira Somoza, Jose AntonioMunch, EtienneRochas, Cyrillehttp://hdl.handle.net/2117/3737702022-10-09T03:44:14Z2022-09-30T10:03:47ZCharacteristic time of strain induced crystallization of crosslinked natural rubber
Candau, Nicolas; Chazeau, Laurent; Chenal, Jean Marc; Gauthier, Catherine; Ferreira Somoza, Jose Antonio; Munch, Etienne; Rochas, Cyrille
Real time Wide-Angle X-ray Scattering (WAXS) measurements during cyclic tensile tests at high strain rates (from 8 s-1–280 s-1) and at room temperature on crosslinked Natural Rubber (NR) are performed thanks to a specific homemade device. From the observed influence of the frequency on the crystallization index at the maximum sample elongation, a characteristic crystallization time is deduced. This is done taking into account the material self-heating during such unusually high strain rates. Two regimes for the dynamic process of strain induced crystallization are evidenced. For the NR tested, the obtained characteristic time is around 20 ms when the material average elongation during the cyclic test is above a critical elongation value ¿c. ¿c is the minimum elongation needed to induce crystallization during low strain rate tensile tests. Moreover, a rapid increase of this characteristic time is found when the average elongation decreases below this critical value.
2022-09-30T10:03:47ZCandau, NicolasChazeau, LaurentChenal, Jean MarcGauthier, CatherineFerreira Somoza, Jose AntonioMunch, EtienneRochas, CyrilleReal time Wide-Angle X-ray Scattering (WAXS) measurements during cyclic tensile tests at high strain rates (from 8 s-1–280 s-1) and at room temperature on crosslinked Natural Rubber (NR) are performed thanks to a specific homemade device. From the observed influence of the frequency on the crystallization index at the maximum sample elongation, a characteristic crystallization time is deduced. This is done taking into account the material self-heating during such unusually high strain rates. Two regimes for the dynamic process of strain induced crystallization are evidenced. For the NR tested, the obtained characteristic time is around 20 ms when the material average elongation during the cyclic test is above a critical elongation value ¿c. ¿c is the minimum elongation needed to induce crystallization during low strain rate tensile tests. Moreover, a rapid increase of this characteristic time is found when the average elongation decreases below this critical value.Strain-induced crystallization of natural rubber and cross-link densities heterogeneitiesCandau, NicolasLaghmach, RabiaChazeau, LaurentChenal, Jean MarcGauthier, CatherineBiben, ThierryMunch, Etiennehttp://hdl.handle.net/2117/3737682022-10-09T03:13:23Z2022-09-30T10:00:15ZStrain-induced crystallization of natural rubber and cross-link densities heterogeneities
Candau, Nicolas; Laghmach, Rabia; Chazeau, Laurent; Chenal, Jean Marc; Gauthier, Catherine; Biben, Thierry; Munch, Etienne
Strain-induced crystallization (SIC) of natural rubber (NR) is characterized during a cyclic deformation at room temperature and low strain rate (~10–3 s–1) using in situ wide angle X-rays scattering (WAXS) measurements. The crystallinity index (CI) and average size of the crystallites in the three main directions are measured during loading and unloading. A scenario describing SIC is then proposed, assuming that SIC corresponds to the successive appearance of crystallite populations whose nucleation and growth depend on the local network density. From this scenario, a methodology, coupling experimental observations and thermodynamic description is developed to determine the distribution of the network chain density associated with the size of a corresponding crystallite population. Finally, complex cyclic tests are performed. They suggest the existence of a memory effect in the chains involved in crystallization, which eases the nucleation process of the crystallites.
2022-09-30T10:00:15ZCandau, NicolasLaghmach, RabiaChazeau, LaurentChenal, Jean MarcGauthier, CatherineBiben, ThierryMunch, EtienneStrain-induced crystallization (SIC) of natural rubber (NR) is characterized during a cyclic deformation at room temperature and low strain rate (~10–3 s–1) using in situ wide angle X-rays scattering (WAXS) measurements. The crystallinity index (CI) and average size of the crystallites in the three main directions are measured during loading and unloading. A scenario describing SIC is then proposed, assuming that SIC corresponds to the successive appearance of crystallite populations whose nucleation and growth depend on the local network density. From this scenario, a methodology, coupling experimental observations and thermodynamic description is developed to determine the distribution of the network chain density associated with the size of a corresponding crystallite population. Finally, complex cyclic tests are performed. They suggest the existence of a memory effect in the chains involved in crystallization, which eases the nucleation process of the crystallites.Strain induced crystallization and melting of natural rubber during dynamic cyclesCandau, NicolasChazeau, LaurentChenal, Jean MarcGauthier, CatherineFerreira Somoza, Jose AntonioMunch, EtienneThiaudière, Dominiquehttp://hdl.handle.net/2117/3737672022-10-09T11:29:08Z2022-09-30T09:53:09ZStrain induced crystallization and melting of natural rubber during dynamic cycles
Candau, Nicolas; Chazeau, Laurent; Chenal, Jean Marc; Gauthier, Catherine; Ferreira Somoza, Jose Antonio; Munch, Etienne; Thiaudière, Dominique
Strain-induced crystallization (SIC) of natural rubber (NR) is studied during dynamic cycles at high frequencies (with equivalent strain rates ranging from 7.2 s-1 to 290 s-1). The testing parameters are varied: the frequency, the temperature and the stretching ratio domain. It is found that an increase of the frequency leads to an unexpected form of the CI–¿ curve, with a decrease of the crystallinity during both loading and unloading steps of the cycle. Nevertheless, the interpretation of the curves needs to take into account several phenomena such as (i) instability of the crystallites generated during the loading step, which increases with the frequency, (ii) the memory of the previous alignment of the chains, which depends on the minimum stretching ratio of the cycle ¿min and the frequency, and (iii) self-heating which makes the crystallite nucleation more difficult and their melting easier. Thus, when the stretching ratio domain is above the expected stretching ratio at complete melting ¿melt, the combination of these phenomena, at high frequencies, leads to unexpected results such as complete melting at ¿min, and hysteresis in the CI–¿ curves.
2022-09-30T09:53:09ZCandau, NicolasChazeau, LaurentChenal, Jean MarcGauthier, CatherineFerreira Somoza, Jose AntonioMunch, EtienneThiaudière, DominiqueStrain-induced crystallization (SIC) of natural rubber (NR) is studied during dynamic cycles at high frequencies (with equivalent strain rates ranging from 7.2 s-1 to 290 s-1). The testing parameters are varied: the frequency, the temperature and the stretching ratio domain. It is found that an increase of the frequency leads to an unexpected form of the CI–¿ curve, with a decrease of the crystallinity during both loading and unloading steps of the cycle. Nevertheless, the interpretation of the curves needs to take into account several phenomena such as (i) instability of the crystallites generated during the loading step, which increases with the frequency, (ii) the memory of the previous alignment of the chains, which depends on the minimum stretching ratio of the cycle ¿min and the frequency, and (iii) self-heating which makes the crystallite nucleation more difficult and their melting easier. Thus, when the stretching ratio domain is above the expected stretching ratio at complete melting ¿melt, the combination of these phenomena, at high frequencies, leads to unexpected results such as complete melting at ¿min, and hysteresis in the CI–¿ curves.EcoBlends’up: PLA/BioPA blends composites, microfibrillated “in situ” through additive manufacturingMartínez Orozco, Leandro IsidroLeón Albiter, NoelCailloux, JonathanSánchez Soto, MiguelMaspoch Rulduà, M. LluïsaSantana Pérez, Orlando Onofrehttp://hdl.handle.net/2117/3673152024-03-10T12:46:47Z2022-05-12T12:47:47ZEcoBlends’up: PLA/BioPA blends composites, microfibrillated “in situ” through additive manufacturing
Martínez Orozco, Leandro Isidro; León Albiter, Noel; Cailloux, Jonathan; Sánchez Soto, Miguel; Maspoch Rulduà, M. Lluïsa; Santana Pérez, Orlando Onofre
In certain polymer blends, a properly oriented microfibrillar morphology of the dispersed phase during the processing stage can generate a reinforcing effect by increasing the fracture toughness, especially in the crack propagation stage. These types of materials are called “in situ” microfibrillated composites (MFCs). Its obtention is conditioned by the rheological properties of the blend and the parameters of the forming process. In this context, additive manufacturing is of interest, specially fused filament fabrication (FFF) by pellets supply instead of extruded filaments. In this work, the study of the feasibility of manufacturing MFCs is proposed by inducing the microfibrillation of a BioPA in the PLA/BioPA “ecoblends”. The optimal processing conditions of the FFF process for the generation of MFCs are evaluated, as well as the uniaxial tensile behavior and the fracture behavior of the manufactured SENB test specimens, employing instrumented impact technique. The evidence obtained shows that the use of a rheologically modified PLA matrix by reactive extrusion (PLAREX) promotes the obtention of MFCs with a better balance of mechanical properties in terms of elastic modulus (E) and ductility and an improvement in apparent toughness and resistance to crack propagation of the fabricated part.
2022-05-12T12:47:47ZMartínez Orozco, Leandro IsidroLeón Albiter, NoelCailloux, JonathanSánchez Soto, MiguelMaspoch Rulduà, M. LluïsaSantana Pérez, Orlando OnofreIn certain polymer blends, a properly oriented microfibrillar morphology of the dispersed phase during the processing stage can generate a reinforcing effect by increasing the fracture toughness, especially in the crack propagation stage. These types of materials are called “in situ” microfibrillated composites (MFCs). Its obtention is conditioned by the rheological properties of the blend and the parameters of the forming process. In this context, additive manufacturing is of interest, specially fused filament fabrication (FFF) by pellets supply instead of extruded filaments. In this work, the study of the feasibility of manufacturing MFCs is proposed by inducing the microfibrillation of a BioPA in the PLA/BioPA “ecoblends”. The optimal processing conditions of the FFF process for the generation of MFCs are evaluated, as well as the uniaxial tensile behavior and the fracture behavior of the manufactured SENB test specimens, employing instrumented impact technique. The evidence obtained shows that the use of a rheologically modified PLA matrix by reactive extrusion (PLAREX) promotes the obtention of MFCs with a better balance of mechanical properties in terms of elastic modulus (E) and ductility and an improvement in apparent toughness and resistance to crack propagation of the fabricated part.Influence of the melt extrusion process on the mechanical behavior and the thermal properties of ethylene vinyl alcohol copolymer by applying the successive self-nucleation and annealing thermal fractionationFranco Urquiza, Edgar A.Santana Pérez, Orlando OnofreMaspoch Rulduà, M. Lluïsahttp://hdl.handle.net/2117/3669782024-03-10T06:46:01Z2022-05-06T11:30:05ZInfluence of the melt extrusion process on the mechanical behavior and the thermal properties of ethylene vinyl alcohol copolymer by applying the successive self-nucleation and annealing thermal fractionation
Franco Urquiza, Edgar A.; Santana Pérez, Orlando Onofre; Maspoch Rulduà, M. Lluïsa
Ethylene vinyl alcohol copolymer was processed three times in a twin-screw extrusion pilot plant in order to reproduce the processing steps required to obtain EVOH nanocomposites. Thin film of the extruded EVOH was prepared by using a cast-film line. The melt flow index and rheological behavior of the film were determined. Viscoelastic parameters were evaluated in a dynamic mechanical testing instrument that revealed the presence of two signals, one attributed to the glass transition temperature and the other one related to the structural modifications associated to interlamellar separation. Thermal properties were evaluated in a differential scanning calorimetry by applying a standard evaluation and successive self-nucleation and annealing approach, finding structural modifications influenced by the melt extrusion process, although the overall percentage of crystallinity degree remains similar. Based on the structural results, the mechanical properties were evaluated considering the ethylene content and resulting on distinct mechanical behavior. Lower ethylene content allows the chain orientation induced during the processing of the film that favors the mechanical performance. Higher ethylene content promotes different deformation mechanisms and a relevant ductility
2022-05-06T11:30:05ZFranco Urquiza, Edgar A.Santana Pérez, Orlando OnofreMaspoch Rulduà, M. LluïsaEthylene vinyl alcohol copolymer was processed three times in a twin-screw extrusion pilot plant in order to reproduce the processing steps required to obtain EVOH nanocomposites. Thin film of the extruded EVOH was prepared by using a cast-film line. The melt flow index and rheological behavior of the film were determined. Viscoelastic parameters were evaluated in a dynamic mechanical testing instrument that revealed the presence of two signals, one attributed to the glass transition temperature and the other one related to the structural modifications associated to interlamellar separation. Thermal properties were evaluated in a differential scanning calorimetry by applying a standard evaluation and successive self-nucleation and annealing approach, finding structural modifications influenced by the melt extrusion process, although the overall percentage of crystallinity degree remains similar. Based on the structural results, the mechanical properties were evaluated considering the ethylene content and resulting on distinct mechanical behavior. Lower ethylene content allows the chain orientation induced during the processing of the film that favors the mechanical performance. Higher ethylene content promotes different deformation mechanisms and a relevant ductilityPoly (Lactic Acid)/Ground Tire Rubber blends using peroxide vulcanizationCandau, NicolasOguz, OguzhanLeón Albiter, NoelMaspoch Rulduà, M. Lluïsahttp://hdl.handle.net/2117/3665292024-03-10T09:14:50Z2022-04-28T12:45:02ZPoly (Lactic Acid)/Ground Tire Rubber blends using peroxide vulcanization
Candau, Nicolas; Oguz, Oguzhan; León Albiter, Noel; Maspoch Rulduà, M. Lluïsa
Poly (Lactic Acid) (PLA)/Ground Tire Rubber (GTR) blends using Dicumyl peroxide (DCP) as a crosslinking agent were prepared with the following aims: propose a new route to recycle wastes rubber from the automotive industry and improve the toughness and impact strength of the inherently brittle bio-based PLA. The GTR were subjected to two types of grinding process (cryo- and dry ambient grinding). Swelling measurements revealed the grinding to be associated with a mechanical damage of the rubber chains, independently on the type of grinding or on the GTR size (from <400 µm to <63 µm). Moreover, the finest GTR contains the largest amount of reinforcing elements (carbon black, clay) that can be advantageously used in PLA/GTR blends. Indeed, the use of the finest cryo-grinded GTR in the presence of DCP showed the least decrease of the tensile strength (-30%); maintenance of the tensile modulus and the largest improvement of the strain at break (+80%), energy at break (+60%) and impact strength (+90%) as compared to the neat PLA. The results were attributed to the good dispersion of both fine GTR and clay particles into the PLA matrix. Moreover, a possible re-crosslinking of the GTR particles and/or co-crosslinking at PLA/GTR interface in presence of DCP is expected to contribute to such improved ductility and impact strength.
2022-04-28T12:45:02ZCandau, NicolasOguz, OguzhanLeón Albiter, NoelMaspoch Rulduà, M. LluïsaPoly (Lactic Acid) (PLA)/Ground Tire Rubber (GTR) blends using Dicumyl peroxide (DCP) as a crosslinking agent were prepared with the following aims: propose a new route to recycle wastes rubber from the automotive industry and improve the toughness and impact strength of the inherently brittle bio-based PLA. The GTR were subjected to two types of grinding process (cryo- and dry ambient grinding). Swelling measurements revealed the grinding to be associated with a mechanical damage of the rubber chains, independently on the type of grinding or on the GTR size (from <400 µm to <63 µm). Moreover, the finest GTR contains the largest amount of reinforcing elements (carbon black, clay) that can be advantageously used in PLA/GTR blends. Indeed, the use of the finest cryo-grinded GTR in the presence of DCP showed the least decrease of the tensile strength (-30%); maintenance of the tensile modulus and the largest improvement of the strain at break (+80%), energy at break (+60%) and impact strength (+90%) as compared to the neat PLA. The results were attributed to the good dispersion of both fine GTR and clay particles into the PLA matrix. Moreover, a possible re-crosslinking of the GTR particles and/or co-crosslinking at PLA/GTR interface in presence of DCP is expected to contribute to such improved ductility and impact strength.Rediseño y sostenibilidad de envasesYlla Gelabert, InésEscolà Gallo, HugoSánchez Soto, MiguelBermúdez Rodríguez, Franciscohttp://hdl.handle.net/2117/3647212022-03-22T10:31:12Z2022-03-22T10:29:05ZRediseño y sostenibilidad de envases
Ylla Gelabert, Inés; Escolà Gallo, Hugo; Sánchez Soto, Miguel; Bermúdez Rodríguez, Francisco
Conceptos como la biodegradabilidad, la reutilización y el reciclaje chocan frontalmente con gran parte de la producción de envases y packaging de los productos que encontramos en el mercado. Atendiendo a las nuevas directrices europeas y nacionales, las recientes modificaciones en la política de sostenibilidad de las firmas y a una mayor sensibilización por parte del público objetivo, son numerosas las marcas que ya han iniciado el proceso de sustitución de sus actuales materiales de packaging por otros que minimicen su impacto ambiental y, por tanto, varíen su huella ecológica. Exponemos en estas páginas el proyecto realizado para una conocida marca del sector alimentario que, además de un rediseño de sus envases, ha requerido la realización de una exhaustiva investigación en las características y el comportamiento de los biopolímeros para adecuarse a las funciones propias de los envases rígidos
2022-03-22T10:29:05ZYlla Gelabert, InésEscolà Gallo, HugoSánchez Soto, MiguelBermúdez Rodríguez, FranciscoConceptos como la biodegradabilidad, la reutilización y el reciclaje chocan frontalmente con gran parte de la producción de envases y packaging de los productos que encontramos en el mercado. Atendiendo a las nuevas directrices europeas y nacionales, las recientes modificaciones en la política de sostenibilidad de las firmas y a una mayor sensibilización por parte del público objetivo, son numerosas las marcas que ya han iniciado el proceso de sustitución de sus actuales materiales de packaging por otros que minimicen su impacto ambiental y, por tanto, varíen su huella ecológica. Exponemos en estas páginas el proyecto realizado para una conocida marca del sector alimentario que, además de un rediseño de sus envases, ha requerido la realización de una exhaustiva investigación en las características y el comportamiento de los biopolímeros para adecuarse a las funciones propias de los envases rígidosHydrostatic pressure dependence in tensile and compressive behavior of an acrylonitrile–butadiene–styrene copolymerVerbeeten, Wilco M. H.Sánchez Soto, MiguelMaspoch Rulduà, M. Lluïsahttp://hdl.handle.net/2117/3633842024-03-10T05:57:21Z2022-03-03T14:10:31ZHydrostatic pressure dependence in tensile and compressive behavior of an acrylonitrile–butadiene–styrene copolymer
Verbeeten, Wilco M. H.; Sánchez Soto, Miguel; Maspoch Rulduà, M. Lluïsa
The strain-rate dependence of a commercial grade ABS copolymer has been analyzed in both compression and tension. By measuring in two loading geometries, the hydrostatic pressure-dependence on the material's deformation behavior can be established. An alternative method to determine pressure-dependence, based on the difference in strain-rate dependence for various loading geometries, has been presented. It was shown to be an effective technique, both for thermorheologically simple materials such as ABS, as well as thermorheologically complex materials, for example, PMMA. A yield criterion, based on an Eyring-type pressure-modified rate equation, has been compared to finite element simulations using the Eindhoven Glassy Polymer (EGP) constitutive model. Although both methods give quantitatively similar results for the yield stress prediction, only the fully 3D EGP model is able to represent the large-strain deformation behavior
2022-03-03T14:10:31ZVerbeeten, Wilco M. H.Sánchez Soto, MiguelMaspoch Rulduà, M. LluïsaThe strain-rate dependence of a commercial grade ABS copolymer has been analyzed in both compression and tension. By measuring in two loading geometries, the hydrostatic pressure-dependence on the material's deformation behavior can be established. An alternative method to determine pressure-dependence, based on the difference in strain-rate dependence for various loading geometries, has been presented. It was shown to be an effective technique, both for thermorheologically simple materials such as ABS, as well as thermorheologically complex materials, for example, PMMA. A yield criterion, based on an Eyring-type pressure-modified rate equation, has been compared to finite element simulations using the Eindhoven Glassy Polymer (EGP) constitutive model. Although both methods give quantitatively similar results for the yield stress prediction, only the fully 3D EGP model is able to represent the large-strain deformation behaviorOrientation of polylactic acid–chitin nanocomposite films via combined calendering and uniaxial drawing: Effect on structure, mechanical, and thermal propertiesSingh, ShikhaKumar Patel, MitulGeng, ShiyuTeleman, AnitaHerrera, NataliaSchwendemann, DanielMaspoch Rulduà, M. LluïsaOksman, Kristiinahttp://hdl.handle.net/2117/3633792024-03-10T09:54:55Z2022-03-03T12:14:41ZOrientation of polylactic acid–chitin nanocomposite films via combined calendering and uniaxial drawing: Effect on structure, mechanical, and thermal properties
Singh, Shikha; Kumar Patel, Mitul; Geng, Shiyu; Teleman, Anita; Herrera, Natalia; Schwendemann, Daniel; Maspoch Rulduà, M. Lluïsa; Oksman, Kristiina
The orientation of polymer composites is one way to increase the mechanical properties of the material in a desired direction. In this study, the aim was to orient chitin nanocrystal (ChNC)-reinforced poly(lactic acid) (PLA) nanocomposites by combining two techniques: calendering and solid-state drawing. The effect of orientation on thermal properties, crystallinity, degree of orientation, mechanical properties and microstructure was studied. The orientation affected the thermal and structural behavior of the nanocomposites. The degree of crystallinity increased from 8% for the isotropic compression-molded films to 53% for the nanocomposites drawn with the highest draw ratio. The wide-angle X-ray scattering results confirmed an orientation factor of 0.9 for the solid-state drawn nanocomposites. The mechanical properties of the oriented nanocomposite films were significantly improved by the orientation, and the pre-orientation achieved by film calendering showed very positive effects on solid-state drawn nanocomposites: The highest mechanical properties were achieved for pre-oriented nanocomposites. The stiffness increased from 2.3 to 4 GPa, the strength from 37 to 170 MPa, the elongation at break from 3 to 75%, and the work of fracture from 1 to 96 MJ/m3. This study demonstrates that the pre-orientation has positive effect on the orientation of the nanocomposites structure and that it is an extremely efficient means to produce films with high strength and toughness.
2022-03-03T12:14:41ZSingh, ShikhaKumar Patel, MitulGeng, ShiyuTeleman, AnitaHerrera, NataliaSchwendemann, DanielMaspoch Rulduà, M. LluïsaOksman, KristiinaThe orientation of polymer composites is one way to increase the mechanical properties of the material in a desired direction. In this study, the aim was to orient chitin nanocrystal (ChNC)-reinforced poly(lactic acid) (PLA) nanocomposites by combining two techniques: calendering and solid-state drawing. The effect of orientation on thermal properties, crystallinity, degree of orientation, mechanical properties and microstructure was studied. The orientation affected the thermal and structural behavior of the nanocomposites. The degree of crystallinity increased from 8% for the isotropic compression-molded films to 53% for the nanocomposites drawn with the highest draw ratio. The wide-angle X-ray scattering results confirmed an orientation factor of 0.9 for the solid-state drawn nanocomposites. The mechanical properties of the oriented nanocomposite films were significantly improved by the orientation, and the pre-orientation achieved by film calendering showed very positive effects on solid-state drawn nanocomposites: The highest mechanical properties were achieved for pre-oriented nanocomposites. The stiffness increased from 2.3 to 4 GPa, the strength from 37 to 170 MPa, the elongation at break from 3 to 75%, and the work of fracture from 1 to 96 MJ/m3. This study demonstrates that the pre-orientation has positive effect on the orientation of the nanocomposites structure and that it is an extremely efficient means to produce films with high strength and toughness.